You may not need a colonoscopy to be selected for colon cancer

In the United States, screening for colorectal cancer is usually unpleasant. A patient's preparation starts with a liquid diet, laxatives and the awkward knowledge of where the colonoscopic camera goes.

But there is another effective way to look for colorectal cancer: fecal immunochemical tests, or FITs, which detect blood in stools (an early sign of cancer). The tests can identify cancer accurately, according to a review and meta-analysis published in the Annals of Internal Medicine.

If the FIT returns negative, the patient is clear until the next annual test. If positive, they will first have a colonoscopy, says study author Thomas Imperiale, researcher at the Rainforest Institute and the Indiana University Center for Health Services and Outcomes Research. "If the equation is a colonoscopy on everyone, you can greatly reduce the use of colonoscopy by doing a FIT," he says. "As long as it can still detect most of the cancers."

The latest study builds on a 2014 review of FIT performance. "At that time, fewer studies were available," said Imperiale. His team's analysis looked at 31 studies, including a total of over 120,000 patients. They found that the tests had a moderate to high sensitivity to cancer, which meant that they had identified cancer if present, and had a low percentage of false positives.

Various studies included in the meta-analysis had different thresholds to a positive test that affected the number of affected cancers. When the test considered 20 micrograms per gram of blood in the sample positive, it identified three out of four cancers, with a low false positive rate, Imperiale said. But when the threshold is lowered to 10 micrograms per gram, sensitivity increases. "You can take the sensitivity to identify 9 out of 10 cancers." However, this causes more false positives.

The analysis showed that although a single FIT can identify cancer, it has a low sensitivity to abnormal growth, known as advanced adenomas, which are considered predecessors for colorectal cancer. It differs from a colonoscopy, which allows doctors to visualize everything from benign cancer growth.

But James Allison, professor emeritus of the University of California, San Francisco and emeritus investigator at Kaiser Permanente, is not worried. He says these adenomas grow very slowly, and only about 6 percent per year will actually become cancerous. As FIT & # 39; s are used annually, a patient with a "negative" result will preferably be tested repeatedly, increasing their likelihood of detecting an adenoma. Colonoscopy, on the other hand, is done only every 10 years. "You have a long time, in a repeated program, before it hurts anyone," said Allison, who published an editorial FIT that accompanied the new study. Not to identify it on the first test is not necessarily a problem, he says, because they are slowly growing, and if they are discovered a year later at a FIT, It probably won't be a big problem.

The easy annual repeatability of FITs is one of the key benefits of the test, says Imperiale. "If you have repeated negative tests, you can start meaningful results and get away with not everyone who needs a colonoscopy." Only about 4 percent of people with adenomas get colorectal cancer. "95 percent of the population will never get it. Negative FITs will identify who those people are." , don't recommend colonoscopy over FIT, or vice versa. Instead, the organization says the goal is to get the highest number of people selected. In other countries, like Canada, FIT is always the first line for colorectal cancer. Patients cannot have a colonoscopy covered by insurance without first having a FIT.

The tests are also much cheaper than colonoscopy, notes Imperial and people are much more likely to do than they might be to do a colonoscopy. many are uncomfortable and stressful.

FITs are not for everyone. Allison will not recommend the test for people with a family history of colorectal cancer or other major risk factors. "I don't think a FIT is appropriate there," he says. Imperial agrees and says the recognition of both options means that patients with different risk factors can make informed choices with their doctors. A patient with a few risk factors and who rarely goes to the doctor may be better off with a colonoscopy, he says. But for a marathon runner in the forefront of preventive investigations, there aren't many colonoscopies. "Patients with low risk can do the best with FIT," he says.

To properly use FIT as a colorectal cancer screening strategy, hospitals and clinics must have systems to test people over the years after a negative test. result Imperiale says. "More importantly, people who are positive should know they need to go in for a colonoscopy," he says.

There are several FIT's available from different manufacturers, with different amounts of information available, and patients should ask their doctors. About the evidence behind the specific version they use, Allison says. The US Preventive Task Force details the FITs with the best performance.

Eventually, this study is a reminder that it does not necessarily require a colonoscopy to enter. "Non-invasive colon cancer tests are a good option for average risk patients," says Imperiale. "There are options, and the only wrong option is to go unprotected."